The two most worrisome areas, says Mr. Aman, are western Long Island Sound, especially around LaGuardia airport, and Raritan Bay, which is close to Newark airport in New Jersey. “The latest NOAA information indicates there could be a 13 foot surge in those areas,” he says. “That would put part of the runways under water.”

The prospect of a surge of water prompted New York to shut down its subway service and close the Holland Tunnel and the Brooklyn Battery Tunnel. On Monday, Mayor Bloomberg said bus and subway service would be shut down on Tuesday, as well. Financial markets will be closed for a second consecutive day Tuesday.